People who spend less time in deep, REM sleep may be more likely to develop dementia

Dementia and the Senses

What you need to know about dementia’s effect on the five senses

As we age, many different changes occur in the body, including changes in the sensory organs that enable us to see, to hear, to touch, to smell and to taste.

With some modifications to the environment and dietary adjustments, most people can adapt.

However, for people with dementia, these sensory changes are confusing, stressful, and can put the person’s safety at great risk.

Vision changes

Pupils size becomes smaller and slower to constrict which creates problems with glare. Reflection of light on anything shiny is too stimulating and a falls risk (Meisami, Brown and Emerle, 2003)
Slowness of pupils to dilate in the dark creates difficulty in seeing where one is going
Visual acuity is less sharp in dim lights, sees shadows, shapes
In dementia, the field of vision can narrow to 12 inches around, almost like wearing binoculars. This means the person has a very limited line of sight. If they cannot see it, it does not exist
When brain processes information that is too stimulating, it reacts by shutting down information from one eye leaving the person with dementia to see with one eye (monocular vision). This loss of depth perception and contrast sensitivity results in the person with dementia doing strange things e.g. exaggerated stepping, picking at air (Snow, 2016)
Colour agnosia reduces ability to differentiate between colours of similar dark or light tones therefore hard to identify objects that are set against a background consisting of similar colours
Most people with dementia find vision changes the most difficult to deal with because the brain does not understand and process the picture/image it is receiving

Plan

Wear glasses
Clear demarcation between floors, walls, toilet and wall/floor
Remove throw rugs, clutter to create clear pathways
Low glare light/automatic lights indoors and outdoors
Avoid busy patterns, checkerboard or zigzag designs
Appropriate footwear, use mobility aide

Hearing changes

Auditory canal narrows, cerumen glands atrophy causing thicker, dryer ear wax that is more difficult to remove and increases hearing impairment
Everyday sounds can become too loud, too stimulating, creating distortion in what the person with dementia hears/understands
Problems with hearing and ear pain will have an impact on person’s ability to concentrate on eating. An interesting study found a correlation between development of ear wax and reduced ability to chew among people who did not have their back teeth (Frasman, 2005)
Many people with dementia have difficulty chewing and this may increase susceptibility to impacted earwax, pain and hearing loss
Difficulty hearing/understanding creates feelings of isolation and frustration

Plan

Clean ears daily, assist with hearing aids
Regular visits to doctor and dentist
Reduce noise in person’s environment
Avoid crowded, busy, noisy areas as too stimulating for person to process
Face person when talking, speak slowly and clearly, write down message, show item

Touch changes

Tactile sensitivity decreases because of skin changes and loss of large numbers of nerve endings particularly in fingertips, palms of hands and lower extremities (Meisami, 1995)
Skin becomes thinner and more susceptible to open areas increasing risk of infection
Inability to distinguish between hot and cold
Decreased nerve endings reduce pain sensitivity, feelings of soreness and discomfort. e.g. pressure ulcer
For some people, any touch to the skin is painful e.g. in the shower, water feels like needles

Plan

Inspect skin and nails, especially toes, look for sores, areas of redness, bluish hues, areas of extreme cold/warm
Identify hot and cold faucets, reduce temperature in hot water tank
Wear footwear indoors/outdoors, wear mittens in cold weather
Ensure sharp corners are padded e.g. table

Sense of smell

Studies have shown that an impaired sense of smell is one of the earliest symptoms of Alzheimer’s and Parkinson’s disease
Of all the senses, age takes the greatest toll on smell perception
Changes in smell are attributed to loss of cells in the olfactory bulbs of the brain and a decrease in sensory cells in the nasal lining
Unable to detect smoke, leaking gas, spoiled food

Plan

Install smoke detectors and gas detector
Write expiry dates on food, check fridge contents weekly

Sense of taste

Taste, along with smell and nerve stimulation determine flavour of foods and helps distinguish between safe and harmful foods.

With age, there is atrophy of the taste buds and decrease in saliva production
As taste buds diminish and insulin in the brain drops, many people with dementia experience changes in appetite and can overuse salt, spices, sugar
Studies have shown when dementia attacks part of the brain responsible for self-restraint in diet, unhealthy cravings increase (Sauer, 2014)
Unable to identify food by taste, including mouldy food, sour milk
May eat toothpaste, mouthwash, household cleaners mistaking them for food

Plan

Remove medications, toiletries, cleaning items
Limit access to salt, sugar, junk food
Wear properly fitting dentures, perform good oral care
Remove any small objects that resemble candies/food
Use saliva substitutes, encourage fluids
See dietician for meal suggestions

The sixth sense
People with dementia, even if unable to communicate, still have an awareness of the world around them, and they can sense when someone is being unkind or disrespectful.

"They may forget what you said, they may forget what you did, but they will never forget how you made them feel." (Maya Angelou).